(A) Toluidine blue stained semi-thin kidney sections from 3 weeks obstructed kidneys showed massive tissue damage with a significant increase in interstitial matrix deposition (red arrows) and damaged tubular epithelium (red arrow heads). In contrast, in released kidneys the interstitial matrix deposition was largely resolved, tubular damage was mitigated and the tissue architecture was restored similar to that of the sham-operated group. Scale bars, 100μm. (B) STEM (Scanning Transmission Electron Microscopy) analyses showed an extensive loss of tubular mitochondria (yellow arrows), increase in the number vacuoles (*), increase in interstitial collagen deposition (cyan arrows), loss of inter-digitating tubular basal lamina (green arrows) and vascular rarefaction (red arrows) in kidneys following three weeks of ureteral obstruction. Release of obstruction led to the disappearance of vacuoles, reduction of interstitial matrix, restoration of mitochondria, basal lamina and vascular structures (Scale bars, 2μm).